AR-15 rifles and similarly styled firearms have become a best-selling category of sporting firearms. However, many AR-15s purchased in the civilian market are not used to fire the originally-chambered NATO 5.56 mm round. Instead, a large number of civilian purchasers also purchase conversion kits for re-chambering their AR-15 style rifles. Although conversion kits exist for a variety of calibers and cartridges, the most common kits convert an AR-15 to fire .22 LR ammunition.
While civilian purchasers have many different reasons for wanting to fire .22 LR ammunition from an AR-15 style rifle, the combined cost of rifle and conversion kit easily (and typically) can exceed $1,000. This relatively high price point limits consumer access to an evidently desirable combination of firearm and ammunition. Even for those consumers who already own an AR-15, and seek to economize on the cost of ammunition (.22 LR rounds are significantly less expensive than are .223 or 5.56 mm rounds), the price of the conversion kit can take a long time to pay back.
By contrast, if an AR-15 style rifle designed to fire .22 LR cartridges was available at a lower price point, consumer acceptance of the firearm would be significantly enhanced.
Additionally, existing .22 LR conversion kits for AR-15 style rifles present several technical issues. First, the AR-15 style gas operated action is intended for 5.56 mm rounds, which provide much larger combustion gas volumes than can be obtained from .22 LR cartridges. An AR-15 style rifle not reliant on gas operation would be preferable for use with .22 LR or other low-power ammunition. Second, the AR-15 style cartridge extractor and deflector do not work optimally with .22 LR casings, which are smaller and lighter than 5.56 mm casings. Third, the existing conversion kits may not reliably engage a last-round bolt catch to lock open the bolt when the magazine has been emptied.
Accordingly, a need exists for a lightweight, low cost AR-15 style sporting rifle designed for firing .22 LR rounds.